pdf № 358, October

DOI: 10.19110/geov.2024.10.1

The article is devoted to the genesis of microcrystalline dolomites of the Kashira and Podolsk horizons of the Moscow stage, which are oil reservoirs in the western part of Bashkortostan. They form consistent layers of low thickness, traceable for tens of kilometers, which determines the relevance of studying the conditions of dolomite formation. Dolomites are composed of crystals 1—10 µm in size with sulfate inclusions and sepiolite admixture. Sepiolites are developed in the intercrystalline space as the finest threads and films enveloping dolomite crystals. A detailed study of sepiolites with a scanning electron microscope with experiments on partial dissolution of dolomites with acid showed an abundance of bacteriomorphs of sepiolite composition. The distribution of REE and Y in dolomites and host rocks is considered. Good convergence in REE spectra is noted for a number of dolomite samples. As a result of the conducted complex of studies, a conclusion is made about the microbial-induced formation of dolomite and sepiolite in the shallowest part of the sea basin with high salinity.

Keywords: primary dolomites, sepiolite, microbially-induced rock formation, REE

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DOI: 10.19110/geov.2024.10.2

In the area of the Yaneytyvis deposit of mineral waters on the Chernov Ridge, three groups of springs with mineralization of 2.3—3.0 g/l and surface waters were tested. The mineral water deposit, the largest in terms of proven reserves in the Arctic zone of Russia, is not exploited. The mineral waters of the springs of the subcryogenic Lower Carboniferous aquifer complex are weakly alkaline, low-mineralized, calcium-sodium chloride. A change in the anionic composition of the waters (a decrease in the proportion of sulfate ion) was established with a constant Cl Ca hydrochemical type. The first data were obtained on the isotopic composition of the mineral waters of the Yaneytyvis springs (dD –111.9...–109.2 ‰ (SMOW), d¹⁸О –15.78...–15.15 ‰ (SMOW), values are close to the thermomineral waters of the springs on the Pymvashor River on the Chernyshev Ridge. Various types of water participate in the formation of the composition of the mineral waters of the springs: fresh waters of modern atmospheric precipitation formed in cold climates and melt waters from degrading permafrost, as well as salty chloride-sodium waters of marine (mixed) genesis of the aquifer complex of carbonate deposits of the Lower Carboniferous. Surface waters of the Bolshezemelskaya tundra in the area of the springs have a diverse composition (HCO₃ Ca–Mg, HCO₃–Cl Ca–Na, Cl Na–Ca, Cl–HCO₃ Mg), their pollution with microelements of natural and technogenic origin has been established.

Keywords: Yaneytyvis spring, underground water, mineral water, hydrochemistry, isotopic composition, Chernov ridge

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DOI: 10.19110/geov.2024.10.3

Mineralogical-analytical methods and methodologies for predictive assessment of solid minerals essentially determine the feasibility and tactics of developing raw materials, and, if necessary, the possibility of replacing, first of all, strategic raw materials with others. Using the example of strategic types of minerals: manganese ores of the Usinsk and bauxite deposits of the Upper Shchugor deposit, the possibilities of mineralogical study of ores with complex composition and structure as part of assessing their quality are considered. The problems and prospects of technological mineralogy in solving problems of mineral resources of strategic metals are identified.

Keywords: technological mineralogy, manganese ores, Usinsk deposit, aluminum-containing ores, Upper Shchugor deposit, strategic metals

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DOI: 10.19110/geov.2024.10.4

Phyllotaxis is an orderly arrangement of leaves on plant stems and branches. Its origin is that each species in the course of evolution optimized the light flux for each leaf. The found optimum was fixed in the genotype and became a phenotypic trait. The possibility to use the crystallographic ideas in botany was shown by A. Bravais. The given paper proposes to describe the arrangement of leaves on a horizontal branch in terms of the theory of borders. All seven possible types of borders are found to be theoretically consistent. The suggested nomenclature in terms of symmetry operations strictly fixes straight and oblique arrangement of symmetrical and asymmetrical leaves on branches. Botanical prototypes have been established for all types of borders.

Keywords: crystallography, systematics and hierarchy of borders, phyllotaxis

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DOI: 10.19110/geov.2024.10.5

This brief report presents the results of our study of the effect of shungite sample thickness (both shungite rocks and vein forms comparable to higher anthraxolites) on their electrophysical properties. The study was conducted by measuring impedance in the frequency range of 0.05–15 MHz. Shungite samples with a carbon content of 96, 95, 73, and 38 at. % and a thickness ranging from 5 mm to 12–15 µm were studied. A significant increase in resistance was found with a decrease in sample thickness to 100 µm or less. In this case, the inductive resistance typical of shungite macrosamples changes to capacitive resistance or only active resistance appears. Thus, it is shown that not only the total content, but also the form and dimensionality of the occurrence of such carbon affects the electrophysical properties of the rock. The obtained results can be used to interpret electrical exploration data of rocks containing disordered carbon (shungites, anthraxolites) in vein and lenticular form, and also to show new prospects for the use of such carbon in the development of functional materials.

Keywords: shungite, electrophysical properties, impedance, microstructure

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